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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2017-2023 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <djwong@kernel.org>
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_log_format.h"
#include "xfs_inode.h"
#include "xfs_icache.h"
#include "xfs_dir2.h"
#include "xfs_dir2_priv.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/readdir.h"
/* Set us up to scrub parents. */
int
xchk_setup_parent(
struct xfs_scrub *sc)
{
return xchk_setup_inode_contents(sc, 0);
}
/* Parent pointers */
/* Look for an entry in a parent pointing to this inode. */
struct xchk_parent_ctx {
struct xfs_scrub *sc;
xfs_nlink_t nlink;
};
/* Look for a single entry in a directory pointing to an inode. */
STATIC int
xchk_parent_actor(
struct xfs_scrub *sc,
struct xfs_inode *dp,
xfs_dir2_dataptr_t dapos,
const struct xfs_name *name,
xfs_ino_t ino,
void *priv)
{
struct xchk_parent_ctx *spc = priv;
int error = 0;
/* Does this name make sense? */
if (!xfs_dir2_namecheck(name->name, name->len))
error = -EFSCORRUPTED;
if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, 0, &error))
return error;
if (sc->ip->i_ino == ino)
spc->nlink++;
if (xchk_should_terminate(spc->sc, &error))
return error;
return 0;
}
/*
* Try to lock a parent directory for checking dirents. Returns the inode
* flags for the locks we now hold, or zero if we failed.
*/
STATIC unsigned int
xchk_parent_ilock_dir(
struct xfs_inode *dp)
{
if (!xfs_ilock_nowait(dp, XFS_ILOCK_SHARED))
return 0;
if (!xfs_need_iread_extents(&dp->i_df))
return XFS_ILOCK_SHARED;
xfs_iunlock(dp, XFS_ILOCK_SHARED);
if (!xfs_ilock_nowait(dp, XFS_ILOCK_EXCL))
return 0;
return XFS_ILOCK_EXCL;
}
/*
* Given the inode number of the alleged parent of the inode being scrubbed,
* try to validate that the parent has exactly one directory entry pointing
* back to the inode being scrubbed. Returns -EAGAIN if we need to revalidate
* the dotdot entry.
*/
STATIC int
xchk_parent_validate(
struct xfs_scrub *sc,
xfs_ino_t parent_ino)
{
struct xchk_parent_ctx spc = {
.sc = sc,
.nlink = 0,
};
struct xfs_mount *mp = sc->mp;
struct xfs_inode *dp = NULL;
xfs_nlink_t expected_nlink;
unsigned int lock_mode;
int error = 0;
/* Is this the root dir? Then '..' must point to itself. */
if (sc->ip == mp->m_rootip) {
if (sc->ip->i_ino != mp->m_sb.sb_rootino ||
sc->ip->i_ino != parent_ino)
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
return 0;
}
/* '..' must not point to ourselves. */
if (sc->ip->i_ino == parent_ino) {
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
return 0;
}
/*
* If we're an unlinked directory, the parent /won't/ have a link
* to us. Otherwise, it should have one link.
*/
expected_nlink = VFS_I(sc->ip)->i_nlink == 0 ? 0 : 1;
/*
* Grab the parent directory inode. This must be released before we
* cancel the scrub transaction.
*
* If _iget returns -EINVAL or -ENOENT then the parent inode number is
* garbage and the directory is corrupt. If the _iget returns
* -EFSCORRUPTED or -EFSBADCRC then the parent is corrupt which is a
* cross referencing error. Any other error is an operational error.
*/
error = xchk_iget(sc, parent_ino, &dp);
if (error == -EINVAL || error == -ENOENT) {
error = -EFSCORRUPTED;
xchk_fblock_process_error(sc, XFS_DATA_FORK, 0, &error);
return error;
}
if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, 0, &error))
return error;
if (dp == sc->ip || !S_ISDIR(VFS_I(dp)->i_mode)) {
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
goto out_rele;
}
lock_mode = xchk_parent_ilock_dir(dp);
if (!lock_mode) {
xchk_iunlock(sc, XFS_ILOCK_EXCL);
xchk_ilock(sc, XFS_ILOCK_EXCL);
error = -EAGAIN;
goto out_rele;
}
/*
* We cannot yet validate this parent pointer if the directory looks as
* though it has been zapped by the inode record repair code.
*/
if (xchk_dir_looks_zapped(dp)) {
error = -EBUSY;
xchk_set_incomplete(sc);
goto out_unlock;
}
/* Look for a directory entry in the parent pointing to the child. */
error = xchk_dir_walk(sc, dp, xchk_parent_actor, &spc);
if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, 0, &error))
goto out_unlock;
/*
* Ensure that the parent has as many links to the child as the child
* thinks it has to the parent.
*/
if (spc.nlink != expected_nlink)
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
out_unlock:
xfs_iunlock(dp, lock_mode);
out_rele:
xchk_irele(sc, dp);
return error;
}
/* Scrub a parent pointer. */
int
xchk_parent(
struct xfs_scrub *sc)
{
struct xfs_mount *mp = sc->mp;
xfs_ino_t parent_ino;
int error = 0;
/*
* If we're a directory, check that the '..' link points up to
* a directory that has one entry pointing to us.
*/
if (!S_ISDIR(VFS_I(sc->ip)->i_mode))
return -ENOENT;
/* We're not a special inode, are we? */
if (!xfs_verify_dir_ino(mp, sc->ip->i_ino)) {
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
return 0;
}
do {
if (xchk_should_terminate(sc, &error))
break;
/* Look up '..' */
error = xchk_dir_lookup(sc, sc->ip, &xfs_name_dotdot,
&parent_ino);
if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, 0, &error))
return error;
if (!xfs_verify_dir_ino(mp, parent_ino)) {
xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
return 0;
}
/*
* Check that the dotdot entry points to a parent directory
* containing a dirent pointing to this subdirectory.
*/
error = xchk_parent_validate(sc, parent_ino);
} while (error == -EAGAIN);
if (error == -EBUSY) {
/*
* We could not scan a directory, so we marked the check
* incomplete. No further error return is necessary.
*/
return 0;
}
return error;
}
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